The present invention relates to a sheet bundle conveying apparatus wherein grip means are used to grip and convey bundled sheets to a predetermined position in a bookbinding apparatus that aligns sequentially supplied print sheets into a bundle and then binding them to a cover sheet with a paste or any other adhesive.
Sheet bundle conveying devices that collect and, for example, align sheets into a bundle and transfer the sheet bundle to a processing position are widely used for various bookbinding apparatus and postprocess apparatus for image forming apparatus. These sheet bundle conveying devices use a grip conveying mechanism that uses gripper means to grip and convey the sheet bundle to the processing position.
A conventional book binding apparatus comprising a grip conveying mechanism is disclosed in Japanese Patent Laid-Open No. 2004-209869. This document proposes an apparatus that stacks and aligns sheets printed by an image forming apparatus, such as a printer or a printing machine, on a stacking tray in order of pages, conveys the bundled sheets to a predetermined paste applying position, and places the sheet bundle with a paste applied thereto, in the cover sheet. The mechanism conveying the sheet bundle from the stacking tray to the predetermined paste applying position uses a pair of grippers, comprising an upper gripper and a lower gripper, to clamp the sheet bundle. The mechanism then moves the grippers along a path to convey the sheet bundle. Moreover, the apparatus disclosed in the document collects bundled sheets on the stacking tray in a horizontal posture, uses the grippers to change the posture of sheet bundle to a vertical one, applies a paste to the sheet bundle in the vertical posture, and conveys a cover sheet to a downstream position where the cover sheet is bound to the sheet bundle.
Consequently, the sheets from the image forming apparatus are collected in a horizontal posture and then moved along the path while being supported in the vertical posture. During this process, the sheets are subjected to sequential bookbinding steps. Thus, in the apparatus disclosed in Japanese Patent Laid-Open No. 2004-206369, when an apparatus error, for example, jamming or power interruption, occurs during the bookbinding process, a sheet bundle that has not been completely processed is left in the apparatus. Then, when the apparatus is restarted, the remaining sheets are removed from the apparatus and a normal bookbinding process is then continued.
As described above, when the grip conveying mechanism conveys the sheet bundle from the stacking tray means to the downstream processing position, if the apparatus is stopped for any reason with the sheet bundle gripped by the grip conveying mechanism, the conventional technique requires the operator to perform a recovery operation, such as removing the sheet bundle gripped by the grip conveying mechanism in order to return the apparatus to its initial state and then restarting the apparatus. However, to remove the bundled sheets from the grip conveying mechanism, the grip force of the grip conveying mechanism must be released. In this case, loosened sheets may fall and scatter in the apparatus. In particular, with the path configuration in which the sheet bundle is conveyed in the vertical posture, if the timing for releasing the grip force of the grip conveying mechanism does not coincide with the timing when the operator receives the sheet bundle, the sheets may fall and scatter. Removal of the fallen sheets is dangerous and cumbersome.
In view of the above problems, an object of the present invention is to provide a method and device for transferring a sheet bundle which, if a bookbinding apparatus is irregularly stopped during a bookbinding process, allows a sheet bundle remaining in the device to be easily removed, preventing the sheets from scattering.
Another object of the present invention is to provide a bookbinding apparatus wherein, when sheets from an image forming apparatus are subjected to an automatic bookbinding process and if the bookbinding apparatus is irregularly stopped, a sheet bundle remaining in the bookbinding apparatus is automatically conveyed to a predetermined takeout position to enable an effective operation without the need to remove the remaining sheets.
The other objects and features of the present invention will be apparent from the description below of embodiments taken in conjunction with the accompanying drawings.